It is recognized that a crucial problem of today's industrial communities is the disposal of solid urban waste (RSU), acid flue gases from thermoelectric power plants burning fuels which have a significant sulphur content, and harmful toxic waste (RTN) from industrial processes, which can neither be released into the environment nor stored at dumping sites, on account of their very low biodegradability and/or toxic nature.
The extensive use of plastics, synthetic rubbers, industrially made paints and dyes, and composite materials has made this problem a dramatic one and dictated recourse to means of breaking down the molecular structures of such materials, mainly by heat application/combustion, and of reducing the materials to elemental substances having simple molecular structures.
The process is carried out in incinerating plants where the heterogeneity of the mostly combustible materials to be incinerated is utilized to feed a first combustion carried out with an external fuel contribution which results in the flue gas attaining temperatures on the order of upwards of 950.degree. C., thereby ensuring decomposition of the volatiles and powders contained in the flue gas.
The heat generated by the combustion process is preferably recovered through steam-generating boilers and exchangers, and distributed to users of various kinds.
Flue gases cannot, however, be exhausted to the atmosphere uncontrollably because they contain significant amounts of such acid BO substances as HC1, HF and SO2.
A similar problem is encountered with thermoelectric power plants, wherein the use of such fuels as coal, lignites, and hydrocarbons which may contain sulphur in non-negligible amounts results in acid flue gases being released which are high in SO2 content.
It is therefore mandatory that the acid substances contained in the flue gas be killed before the latter is exhausted to the atmosphere.
The killing is accomplished on bulky and expensive scrubbing towers.
Due to the low operating temperatures (&lt;100.degree. C.), these represent the last component before the chimney, so that the whole system is swept by flue gas laden with acid substances, with attendant serious corrosion effects especially on the tube nest of the boiler.
The scrubbing waters, moreover, require to be processed for separation of the acid substances to prevent these from being passed into the environment, in the instance of scrub water open-flow systems, or for saturating the scrubbing liquids, in the instance of closed-circuit systems.
This process is the more expensive and the involved equipment the bulklet, the higher is the flow-rate of the flue gases being handled.
Thus, conventional incinerating plants and thermoelectric power plants are high in volume and cost, and liable to rapid deterioration, whereby additionally to involving continued careful maintenance work, they require frequent overhauling.
The latter can only be carried out, of course, with the system shut down and cold, which involves prolonged off-duty during which time, if a build-up of the waste material is to be avoided, this must be re-directed to backup plants at added transport costs, or multiple incinerating plants must be provided which can be shut off in turns.